1. Field of the Invention
This invention relates generally to an endoscope apparatus, and more particularly to an endoscope apparatus that can be disinfected with satisfactory results.
2. Description of Related Art
An endoscope apparatus is provided with members such as an air/water supply button and a suction button, which are arranged at a scope operation part, a forceps aperture plug used for a forceps aperture formed in a scope holding part, a variety of caps provided at an auxiliary water supply channel, etc., a water supply tank, and the like provided as the need arises. These members include many parts made of conventional rubber material such as nitrile rubber (NBR), silicone rubber and fluorocarbon rubber (copolymer of vinylidenefluoride and hexafluoropropylene).
The endoscope apparatus for medical use must be disinfected completely. The endoscope apparatus is ordinarily disinfected according to guidelines issued by medical societies and the like. According to the guidelines, the endoscope must be disinfected with the highest standards, and glutaraldehyde and ethylene oxide gas (EOG) are recommended as disinfectant. However, these disinfectants are highly toxic, and they may damage the health of the operator and may cause damage to the environment as well. It is therefore undesirable to use these disinfectants.
Accordingly, new types of disinfectant have been increasingly used such as peracetic acid (CH3COOOH), plasma of hydrogen peroxide (H2O2), and acid water, which after use become water, air or harmless substances. These new types of disinfectant have powerful oxidizing properties, and may cause the rubber parts of the endoscope to corrode. For example, NBR cannot resist the new types of disinfectant at all. Although fluorocarbon rubber has relatively high chemical resistance, it may crack, swell and the like if the endoscope apparatus is exposed to the new types of disinfectant for a long time. Silicone rubber has a high chemical resistance; however, it has a low mechanical strength and is not suitable for all rubber parts of the endoscope apparatus.
Ethylene-propylenediene terpolymer (EPDM) has both a high chemical resistance and a high mechanical strength, and it has been increasingly used for the rubber parts of the endoscope apparatus. EPDM, however, is easily affected by heat and is only resistant to 135xc2x0 C. under normal pressure. Hence, the rubber parts made of EPDM are not suitable for the autoclave sterilization in which steam of 132xc2x0 C. under pressure of 200 kPa effects sterilization. The autoclave sterilization is authorized by the guidelines. Recently, at least the parts detachable from the body of the endoscope apparatus are required to be sterilized in the autoclave.
It is therefore an object of the present invention to provide an endoscope apparatus that can be sterilized in the autoclave and disinfected with the new types of disinfectant having powerful oxidizing properties such as peracetic acid.
To achieve the above object, the present invention provides an endoscope comprising: a rubber part made of vulcanized rubber material having a perfluoromonomer structure of which an average molecular weight is not greater than 2000.
The material having the perfluoromonomer structure is a copolymer that is obtained by completely replacing hydrogen atoms with fluorine atoms. The perfluoromonomer material is usually used as fluoroplastics, and the usual perfluoromonomer material has no rubber properties such as ductility and elasticity.
According to the present invention, the rubber parts of the endoscope are made of a perfluoromonomer rubber material, which is softened by using the perfluoromonomer material with average molecular weight of not greater than 2000 and is vulcanized. The perfluoromonomer rubber material has rubber characteristics such as ductility and elasticity and the same characteristics as fluoroplastics. More specifically, the perfluoromonomer rubber material has a high heat resistance, a high chemical resistance, a high mechanical strength and a high smoothness, and is nontoxic. The endoscope of the present invention has the rubber parts made of the perfluoromonomer rubber material, and can be both sterilized in the autoclave and disinfected with the new types of disinfectant having powerful oxidizing properties.
Preferably, the average molecular weight of the perfluoromonomer rubber material is not less than 1000 in order to prevent the manufactured rubber parts from becoming softened excessively.